Instant adhesives, or cyanoacrylates, cure very quickly when confined between surfaces. Surface humidity on the substrates triggers the cure reaction, which moves from the substrate surfaces towards the middle of the adhesive joint. Cyanoacrylates are typically chosen for bonding small to medium-size parts to achieve extremely fast curing. Due to their limited gap-filling capacity, they require close-fitting surfaces. Their adhesion to most substrates is excellent and the bonding strength in shear and tensile mode is very good. They should not be used on float glass or glazed ceramics, but can be used on GRP. Bonds continuously exposed to water need proper adhesive selection and ageing evaluation.